Work-holding means



Nov. 9 1926.

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G. BROWN WORK HOLDING MEANS 1 Filed NOV. 27 1925 2 Sheets-Sheet 2 Patented Nov. 9, 1926.

' GREGORY BROWN, or BRIDGEroRnco'NNEcTIcUr, ASSIGNOR TO MARQUET'IE TOOL &

MANUFACTURING C0,, OF CHICAGO, ILLINOIS, A COBPORATIONOF ILLINOIS.

WORK-HOLDING MEANS.

Application filed November 27, 1925. Serial Ito. 71,587.

In the drawing and pressing of sheet metal by means of dies and shaping it into the desired forms, it is necessary, during the shaping operation to hold the marginal portion of the blank, or that portion adjacent to the forming block, between two moving members suitably pressed together, otherwise, the metal will not be properly drawn or stretched, or the margin of the blank will be wrinkled or .folded, the two cooperating members operating to force the metal over a forming block or. die.

Various cushioning means have heretofore been employed for this purpose and in v some instances very'satisfactory results have been accomplished, but in other instances the means provided for, this purpose have been unsatisfactorytbecause as the pressure ring descends, the pressure exerted on it by the cushioning means increases, causing the margin of the blank to be gripped so securely and unyieldingly that the metal 'being drawn will tear and break, with the result that the article will be damaged.

If it is attempted, with some of the prior devices. to employ a lesser pressure then the margin of the blank will not be held securely enough to prevent the metal from wrinkling or cracking.

.It is one of the objects of the present invention to overcome these difficulties and objections and to provide electro-magnetic means operating upon the blank holding member to cause the same to grip the work and hold it with the desired degree of pressure, which will hold-the work suificiently tight to permit it tb be shaped or drawnand at the same time prevent the margin from wrinkling or cracking while the metal is being drawn or shaped.

A further object is to provide in an electro-magnetic work holder of this character means whereby the intensity of the magnetic field may be varied at will, thereby enabling an extremely wide range of pressure of the work holding means to be obtained.

To the attainment of-these ends and the accomplishment of other new and useful objects as will appear, the invention consists .in the features of novelty in substantially the construction, combination and arrangement of the several parts hereinafter more fully described and claimedand shown in the accompanying drawings illustrating this invention, and in whichi Figure 1 is a view partly in elevation, partly in section and with parts omitted of a sheet metal shaping machine constructed in accordance with the principles of this invention and showing the electro-magnetic .cushioning means operating to influence the draw ring, and with the parts in one position. I g Figure 2 is a view similar to Figure .1 showing the parts in another position. Figure 3,is a view similar to Figure 1 of another form of the invention.

Figure 4 is a view similar to, Figure 3 showing the parts in a different position.

Referring more particularly to the drawings and to the form of the invention as shownin Figures 1 and 2, the numeral 1.0 designates generally a bolster or bed plate of the machine upon which is mounted in any suitable manner a die or block 11, over which the material 12 is adapted to be shaped. A draw ring 13 is provided which encompasses the block' or die 11, and this draw ring co-operates-with a portion of a shaping or forming die 14'to clamp the edge a or margin of he' material therebetween and to hold the same during the shaping or .forming operation. The die or forming block 13 is connected with a reciprocating member 15 of thepress and this member 15 is given a reciprocating movement in any desired or suitable manner (not shown) and Whichis well known in this art.,

'An 'electro-magnetic device 16, preferably in the form of a magnet is connected with the reciprocating member 15 preferably by means of bars or rods 17 that ass through the bed or bolsterplate 10 of t e press and extend for a considerable distance therebelow so that the magnet 16 will be disposed below the bolsteror bed plate 10. i An armature 19 is provided which co-' 7 operates with the magnet 16 and the armature has connected with it pins or rods 20,

which latter are preferably supported by means of a cross bar or member 21 of nonmagnetic material, which in turn is connected by means of connecting rods or supports 22 with the armature. The armature is preferably arranged beneath the magnet 16 and 105 the bars r p ns 20 p through th bed 4 plate of the machine and contact with i position as shown in Figure 2, the

' rality of different windings 27 having. contact points 28 with which a switch device 29 arranged in the circuit 23, is adapted to cooperate.

A knock out device 30 ofany desired and.

well known construction may be provided for knocking out or ejecting the shaped article from the die 14 and which knock out device, is adapted to be automatically operated at a predetermined point in the cycle of operation of the machine (not shown) and which is-well known in this art. i

In operation when the ram 15 and die 14 i are in a raised position with respect to the.

forming block 11, the parts will assume the aw ring 13 being held in its uppermost position and with its face flush with the upper face of'the'forming block or die 11, by means of the magnet 16 attracting thearmature 19,

the contacts" 25 and 26 being so arranged that-the magnet will be energized at the proper time. If necessary and as anadditional means for holding the draw rin 13 with the upper ace of the forming block in its uppermost osition with its face ush springs 21 may be employed. a

The work 12 -'s then placed in position upon theforming die 11 and the blank hold er 13. As the ram 15\and die 14 descend the work' 12 will be clamped between the i draw ring 13 and the adjacent face of the.

die 14. 'A further -movement of the ram and die 14 in the 'samedirection will cause the material to be shaped over the die or forming block 11, as shown in Figure 1.

The strength of the magnetis so regulated that, the material 12 will be gripped between the draw ringand the die 14 with sutficient force topermit the article to be shaped and to hold the marginal portion of the article from wrinkling or cracking during the forming operation.

As the ram and die 14 recede the draw ring 13 will follow the movement ofthe die 14 and the article will bestripped from the :forming block 11 and carried upwardly in. the die 14 until it is ejected by the knock out device 30.

In the Figures?) and 4 the armature 31 has connected with it a blank holding member 32 through the medium, 9f b p eting bars or al be varied and form of theinvention shown in rods 33, the blank holding member co-operating with the die 34 into which a die 35 operates. The magnet 36 when energized will attract the armature 31 and through the .medium of the rods 33 will draw the clamping member 32 against the work 31 so that the latter will be clamped between the edge of the die 34 and the blank holding member 32. Any suitable means may be provided for automatically opening and closing the C11- cuit to de-energize and energize the'magnet, I

and for that purpose there may be provided a contact 25 which is connected with a reciprocable part oithe pressand which is arranged within the circuit. This contact 25 is adapted to co-operate with another contact 26 in the circuit.

If desired suitablesprings 38 of the fdesired size and stren h may be employed to raise the blank holdm member 32 after the forming operation an to permit the insertion of a new piece of material.

The blank holding member 32 may also be raised in .any suitable manner such as by means others or rods 39 connected with the ram 40 or any movable. part of the press.

These rods pass loosely through a portion of the blank holding member 32 and have connected therewith nuts 41 so .spaced that as the ram 40 and die 35 descend they will pass 7 loosely through the blank holding member 32 so as not to interfere with the operation of thelatter. Upon the receding movement of the ram'40 and the die 35 the nuts or collars 41 will at a predetermined point inthe cycle of operation of' the machine engage 'and raise the blank holding member 32 to the position shown in Figure 4, so as to permit the removal of the finished article. -;Knock out ,pins 42 may be'connected to move with the armature 31 so as to knock out the completed article from the die 34.

. In this form of the invention the strength of the magnet 36 may be varied in the same manner as that shown in connection with Figures ,1 and 2.

With the invention herein disclosed it will be manifest that an extremely wide range of pressure upon the work may be obmachine now on the market. Furthermore with this invention it will be manifest that the ram of the press-does not operate against the stress of the magnet as the magnet and armature together with the connected parts, in the form ot-the invention shown in Figures 1 and 2, move as a unit with the ram. It may be desirable tained and may be readily attached to any under some conditions of operation to vary the gri or pressure of theblank holding means" riving the stroke or operation of the press and in order to accomplish this, means may be provided for automatically varying the intensity of-the magnetism in the magnet. To that end there may be provided a I earn element 43 adjustably mounted upon a movable part of the press such as the ram -to eo-operate with a rheostat lever 44. The lever 44 is mounted upon a'stationary part of the press and co-operates with a rheostat winding 45, and the lever is con-.1

trolled by a spring 46. In operation asthe slide 15, of the press starts its downward movement, the cam 43 engages the lever 44 and the rheostat 45 is operated with the result that the magnetism in the magnet will be varied thereby varying-"the pressure on the work holding or gripping means. The spring 46 will operate on the back or up stroke of the slide 15 to move the lever 44 back to its normal position afterthe completion of the return stroke of the press.

While the preferred forms of the inven-- tion'have been herein shown and described, it is-to be understood that various changes may be made in the details of construction and in the combination and arrangement of the several parts, within the scope of the claims, without departing from the spirit of this invention. A

What isclaimed as new is 1. The combination of a sheet material shaping member, means co-operating ith said member for shaping the material ndembodying gripping means for the material,

, and elcotro-magnetic means for maintaining a pressure on the gripping means during the operation of shaping the material.

2. The combination of a sheet material shaping member, means co-operating with said member for shaping the material and embodying gripping means for. the material, and electromagnetic means for maintaining a substantially unvarying' pressure on the shaping member, means co-operating with. said member for shaping the material and embodyinggripping means for the material, clectro-magnetic means for maintaining a pressure on the gripping means during the operation of shaping the material, and means for varyin at will the intensity of the field of the sa1d electro-magnetic means.

5. The combination of a sheet material shaping member, means co-operating with said member for shaping the material and embodying gripping means for thematerial,

and means for maintaining a pressure on.

the gripping means during the operation of shaping the material, the sa1d pressure maintaining means embodying a magnetand an armature one of which isoperatively connected with one of the parts of the' said gripping means.

6. The combination of a sheet material shaping member, means (Jo-operating with said member for shaping the material and embodying gripping means for the material. means for maintaining a pressure on the gripping means during the operation of. shaping the material, the said pressure maintaining'means embodying a magnet and an armature one of which 1s operatively connected with one of the parts of the said gripping means, and means for varying at will'the intensity of the field of the magnet.

7. The combination of a sheet material shaping member, means co-operating' with said member for shapi g the material, and embodying gripping means for the material, means for maintaining a pressure on the gripping means during the operation of shaping the material, the said pressure maintaining means embod ying'a magnet and an armature one of which is operatively connected with one of the parts of the said gripping means, and means operating automatically to render. the said" magnet active and inactive.

8. The combination of a sheet material shaping member, means co-operating with said member for shaping-the material and embodying gripping means for the material, electro-magnetic means for maintaining a pressure on the gripping means during the operation of shaping the material,-.and

means operating automatically to render the sa1d electro-magnetic means active and inactive.

. 9. The combination of a sheet materialshaping member, means co-operating with said memberfor shaping'thematerial and embodying gripping means for the material. and electro-magnetic means for maintaining a pressure on the gripping means during the operation .of shaping the material, the said elect'ro-magnetie means moving as a unit with the first recited means and the said gripping means during theshaping operation. K

10. The combination of a sheet material "shaping member, means co-operating with said member for shaping the material and embodying gripping means for the material electro-magnetic means for maintaining a pressure on the gripping means during the o eration of shaping the material, the said e ectro-magnetic means moving as a unit with the second recited means and the said gripping means during the shaping operation, and means operating automatically to energize and deenergize the said electromagnetic means.

lUil' 11.'The combination of a sheet material shaping member, means co-operating with said member for shaping-the material and embodying gripping means for the material, electro-magnetic means for maintaining a pressure on the gripping means during the operationof shaping the material, the said electro-magnetic means moving as a unit with the second recited means and the said gripping means during the shaping operation, and means for varying at will'the degree of pressure of the said gripping means.

12. The combination 'of-a sheet material shaping member, means co-oprerating with said member for shaping the material'and embodying gripping means forthe material, and means for maintaining a pressure on the gripping means during the operation of shaping the material, said pressure maintaining means embodying a magnet and an armature one of which is connected with the gripping means, all of said parts moving as a unit during the operation of shaping the material. N

13. The combinationof a sheet material shaping member, means c'o-operatiilg with said member for shaping the material and embodying gripping means for the material,

'means for maintaining apressure on the gripping means during the operation of shaping the material, said pressure tmaintaining means embodying a magnet and an armature one of which is connected with the gripping means, all of said parts moving as aunit during the operation of shaping the material, and means operating automatically to render the said magnet active and inactive. I

- 14. The combination of a sheet material shaping member, means .co-operatingwith said'mem'ber for shaping'the material and embodyinggripping means for the material, means for maintaining a pressure on the gripping means durlng the operation of shaping the material, said pressure maintaimng means embodying a magnet and an armature one of'which is connected with the gripping means, all of said parts moving as a unit during the operation of shapingthe material, and means for varying at will the intensity ofthe field of the said. magnet.

15. The combination of a sheet material I November, A. D. 1925. v

'. GREGORY BROWN.

said member for'shaping the material and embodying gripping means for the material, eleotro-magnetic means for maintaining a pressure on the gripping means during the operation-of shaping the material, and meansshaping member, means co-operating with operating automatically'to vary the degree of pressure of the said gripping means during the stroke of the press;

16. The combinationof a sheet material shaping member, means co-operating with said member for shaping the material and embodying gripping means for the material, electro-magnetic means for maintaining a pressure on the gripping meansv during the matically operating means for varying the intensity of the electro-magnetic means at predetermined points in the cycle of operation of the press.

operation of shaping the material, and auto- 17. The combination of a sheet material shaping member, means co-operating with said member for shaping the material and embodying gripping means for the material,

means for maintaining a pressure on the gr pping v means during the operation of shaping the material, the said pressure main- Y I taining means embodying amagnet and an armature one. of which is operatively connected with one of the parts of the said gripping means, and means operating auto-- matically during the stroke of the press to vary the intensity of the said magnet.

18. The combination of a sheetmatenal' shaping member, means co-operating with said member for shaping the material and embodying gripping means for the material,

means *for' maintaining a pressure on the.

gripping means during the operation of shaping the material, the said pressure maintaining 'means' embodying a magnet and an armature one of which is operatively connected with one of the parts of the said g'r1pping means, means operating automatically during the stroke of the press to vary. the in-;

nsity of the said magnet, andmeans f0 rendering the magnet inactive and more 0. less active.

In testimony whereof I have si ned my name-to this specification, on this 6t day of 4 

